Battery electric trucks require battery cooling systems which, due their sizing requirements, can only be packaged in the pickup box. In order to limit the loss of cargo space in the box, the cooling system or battery cooling pack is packaged between the box side outer and box side inner panels. In addition, the box side outer panel is designed to function as an access panel to allow generous access for the installation, assembly and service of the battery cooling pack. Further, the compartment defined between the box side inner panel and box side outer panel is adapted as a storage space that may be customized by the motor vehicle operator to neatly and conveniently store any desired items.